Damper disc having annular protrusions and recesses

ABSTRACT

The present invention discloses a damper disc comprising a spline hub; a radial flange formed at the hub; a case connected to facings; circumferentially spaced plural compressible coil springs connecting the case and the flange together; sealed spring chambers formed around the springs by the case or a cover; sealed narrow spaces connecting the spring chambers together; and spring seats disposed at both ends of the springs; said chambers and spaces being filled with oil, so that the oil applies a resistance force to the moving spring seats. At least one of side surfaces of a portion of the flange radially inside the springs may be provided with radially spaced annular protrusions, and the cases may be provided with annular protrusions engaging with the protrusions on the flange with narrow spaces therebetween.

This is a division of application Ser. No. 418,771 filed Sept. 16, 1982,now U.S. Pat. No. 4,601,676.

BACKGROUND OF THE INVENTION

The present invention relates to a damper disc in which a shock absorberof hydraulic type is arranged so as to effectively absorb a torsionalvibration for improving a starting feeling of a vehicle.

Generally, a clutch disc of an automobile has been provided with adamper disc of frictional type including friction washers. However, suchdamper generates a fixed torque hysteresis independently of a relativetorsion speed between a driving side and a driven side. Therefore, whendamping characteristics are determined so as to achieve a good startingfeeling, torsional vibration in high speed driving can not effectivelybe absorbed.

Accordingly, it is an object of the invention to provide an improveddamper disc, overcoming the above-noted disadvantages, in which a shockabsorber of hydraulic type is arranged.

Other and further objects, features and advantages of the invention willappear more fully from the following description of the preferredembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional partial view of a clutch disc of an embodimentaccording to the invention;

FIG. 2 is a partially cut-away elevation viewed in a direction of arrowsII--II of FIG. 1;

FIG. 3 is a sectional view taken along line III--III of FIG. 2;

FIG. 4 is a sectional view taken along line IV--IV of FIG. 2;

FIG. 5 is a graph of torque characteristics;

FIG. 6 is a graph explaining relations between transmitted torque andhysteresis torque at various torque frequencies;

FIG. 7 is a sectional view of a clutch disc of another embodimentaccording to the invention;

FIG. 8 is a partially cut-away partial elevation viewed in a directionof arrows VIII--VIII of FIG. 7;

FIG. 9 is a sectional view taken along line IX--IX of FIG. 8;

FIG. 10 is a graph of transmitted torque characteristics;

FIG. 11 is a sectional partial view of a clutch disc of anotherembodiment according to the invention;

FIG. 12 is a partially cut-away partial view viewed in a direction of anarrow XII of FIG. 11;

FIG. 13 is a sectional view taken along line XIII--XIII of FIG. 12;

FIG. 14 is a graph of transmitted torque characteristics;

FIG. 15 is an axially viewed sectional partial view of a clutch disc ofstill another embodiment of the invention; and

FIG. 16 is a sectional partial view taken along line XVI--XVI of FIG.15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a spline hub 1 splined to an output shaft (notshown) has a radial flange 2. Both side surfaces of the flange 2 arefully covered by a pair of cases 3 and 4, which have a larger diameterthan the flange 2. Radially outer portions of the cases 3 and 4 areconnected together by circumferentially spaced rivets 5 with an annularring 6 and an annular seal 6a therebetween. The rivets 5 fix cushioningplates 7 to the case 3. A pair of friction facings 8 are fixed to bothsurfaces of the cushioning plates 7 by rivets 9. The cases 3 and 4 havecylindrical flanges 10 and 11 at their inner peripheries. Annular seals12 are disposed between the flanges 10 and 11 and the outer peripheralsurface of the hub 1. Both cases 3 and 4 are connected together bystopper pins 13 which extend through recesses 15 in the flange 2.Washers 14 are fitted around each pin 13. Annular seals 16 are arrangedaround each pin 13 and between the washers 14 and the cases 3 and 4.Circumferentially extending compressible coil springs 17 and 18 arearranged in openings 20 in the flange 2. The springs 17 have largediameter, and the springs 18 have small diameter. A pair of the springs17 and 18 are coaxially arranged. Side portions of the springs 17 and 18protruding from the openings 20 are covered by hollows 21 and 22 formedin the cases 3 and 4.

Referring to FIG. 2, a disc is provided with two sets of the springs 17and 18 and two compressible coil springs 19 which are alternatelyarranged and circumferentially equally spaced. When the cases 3 and 4 donot twist or torsionally turn with respect to the flange 2 as shown inFIG. 2, one end of each spring 18 is in contact with a small spring seat24 having an integral guide pin 23. Each seat 24 contacts onlyprojection 30 and the inner circumference of spring seat 33. The otherend of each spring 18 is in contact with a spring seat 29 having anintegral guide pin. Each seat 29 is supported through a spring seat 31by a side edge 32 of the opening 20 and the inner end surfaces 26 and 27of the hollows 21 and 22 as shown in upper right portion in FIG. 2. Withrespect to a disc rotating direction A, the seats 24 are positioned infront of the springs and the seats 29 are positioned in back. An end ofeach spring 17 is in contact with the radially outer portion of thespring seat 31. The other end of each spring 17 is supported through anannular spring seat 33 by the inner end surfaces 26 and 27 of thehollows 21 and 22. The spring seats 33 are slidably fitted around theseat 24. A circumferential space corresponding to a torsion angle of 3°is spaced between each seat 33 and hollow portions of each side edge 25which are radially inside and outside portions to the projection 30.Both ends of each spring 19 are supported through spring seats 35 by theside edges 25 of the opening 20 as shown in left portion in FIG. 2.Spaces corresponding to a torsion angle of 6° are formed between thespring seats 35 and the inner end surfaces 26 and 27 of the hollows 21and 22. The spring seat 31, 33 and 35 have similar outer peipheralshape, and are slidably and closely fitted to inner surfaces of thehollows 26 and 27 and radially outer and inner edges of the openings 20.The seats 31, 33 and 35 have portions 36 projecting radially inwardly.

Referring to FIG. 3, spring chambers 40 in which the springs arearranged and spaces 41 between the cases 3 and 4 and the flange 2 arefilled with operating oil. As shown in FIG. 4, an inlet port 42 (a drainport) is formed in the hollow 22 and is closed by screw 43 (a plug)which is screwed into a nut 44 welded to the case 4.

One of the specific functions or operations of the disc can be asfollows. When the clutch is engaged, a torque in a rotating direction Ais transmitted from a flywheel to the facings 8. The torque is thentransmitted to the cases 3 and 4 and further transmitted through thesprings 17, 18 and 19 to the flange 2, hub 1 and the output shaft. Inthis operation, the springs 17, 18 and 19 are compressed, so that thecases 3 and 4 are torsionally turned in the direction A with respect tothe flange 2. While the torsion angle D is smaller than 3° (O-P1 in FIG.5), only the small spring 18 among the springs 17, 18 and 19 transmitthe torque and are compressed, thus, as shown at alternate long and twoshort dashes Y in FIG. 5, an increasing rate ofspring-transmitted-torque, which is transmitted only through thesprings, is kept small with respect to increase of the torsion angle D.When the torsion angle D reaches 3°, the annular spring seats 33 contactwith the side edges 25 of the openings 20. Thus, until the torsion angleD reaches 6°, the torque T is transmitted through the springs 17 and 18,and the increasing rate of the spring-transmitted torque with respect tothe torsion angle D is kept large as shown at section P1-P2 in FIG. 5.When the torsion angle D reaches 6°, the spring seats 35 contact withthe inner end surfaces 26 and 27 of the hollows 21 and 22, so that thetorque T is transmitted through all of the springs 17, 18 and 19,thereafter. Thus, the increasing rate of the spring-transmitted-torquewith respect to the torsion angle D is kept further larger, as shown atsection P2-P3 in FIG. 5. When the torsion angle D reach 9°, the stopperpins 13 contact with the edges of the recesses 15, so that furthertorsion is prevented.

In the above operation, the spring seats 29, 31 and 33 move rightward inFIG. 3 and function as pistons which push and discharge the oil in thechambers 40 into the spaces 41. The oil, which is being dischargedtoward the spaces 41, flows through narrow spaces between the outerpeipheries of the spring seats 31 and 33 and the hollows 21 and 22 inFIG. 1, which applies a resistance force against the spring seats 31 and33. The oil also applies the resistance force against the spring seat 35in FIG. 2. The resistance force applied to the spring seats 31, 33 and35 is transmitted to the twisting cases 3 and 4, so that a hysteresis his added to the characteristic Y, which forms an actual torquecharacteristic X. The illustrated characteristic X is acquired when thetorsional angular speed or turning speed is fixed. When the torsionalangular speed changes and the relative moving speed of the seats 31, 33and 35 changes, a flowing speed of the oil also changes, so that theresistance caused by the oil changes. Thus, the hysteresis h changes inaccordance with the change of the torsional angular speed. FIG. 6illustrates relations between the hysteresis h and the torques T1 ofwhich frequencies are 20, 40, . . . 140 and 147 Hz, respectively. Asapparent from FIG. 6, the hysteresis h changes when the torque T1 andthe frequency which corresponds to the torsional angular speed changes.

In the embodiment detailed hereinbefore, the characteristic X includingthe hysteresis h is acquired also in a negative area. The membersincluding the springs 17, 18 and 19 as well as the recesses 15 andothers are so constructed that the increasing rate of the torque Tchanges at two steps and that a maximum torsion angle D is 5° in thenegative area.

According to the invention, as stated hereinbefore, the disc includesthe shock absorber of the hydraulic type, in which the hysteresis torquechanges in accordance with the change of the torsional angular speed.Therefore, torque vibrations both in high speed driving and the startingand stopping operation can effectively be absorbed. The oil can easilybe exchanged for oil having other viscosity so as to change thehysteresis characteristic for constructing the damper discs respectivelysuitable for various uses.

Following modifications may be employed.

Referring to FIGS. 7 and 8, a flange 51 of a spline hub 50 has a smalldiameter. An annular member 53 having substantially same thickness s theflange 51 is rotatably fitted to a peripheral surface 52 of the flange51. The member 53 is provided with recesses 54 opened radially inwardly,in whch circumferentially extending compressible coil springs 55 and 56are coaxially arranged, respectively. Both sides of the springs 55 andthe flange 51 are covered by a pair of covers 57 and 58. The covers 57and 58 and a radially outer portion of the member 53 are covered by apair of cases 60 and 61. Annular seals 59 (FIG. 7) are disposed betweenthe hub 50 and the cases 60 and 61. The cases 60 and 61 and the member53 are fixed together by pins 62 with annular packings 63 therebetween.The pins 62 also fix cushioning plates 7 to the case 60. Pins 66connecting the cases 60 and 61 together are inserted into long apertures67 in the flange 51 and the coveres 57 and 58, respectively. A washer 64and a seal 65 are arranged around each pin 66. As shown in FIG. 8,circumferential spaces are formed between each pin 66 and the inner edgeof the aperture 67. These spaces are angularly longer than maximumtorsion angles of 7° (FIG. 10) in a rotation direction A and 5° in thereverse direction. As shown in FIG. 7, both coveres 57 and 58 are fixedto the flange 51 by pins 69. Both covers 57 and 58 are also connectedtogether by pins 68, which extend through long apertures 70 in theflange 51. Circumferential spaces are formed between each pin 68 and theinner edge of the aperture 70. These spaces correspond to the maximumtorsion angles of 7° and 5°. An oil inlet 71 is formed by a nut 73welded to the inner surface of the case 61, and is closed by a plugscrew 72. An interior in the cases 60 and 61 is filled with oil suppliedthrough the inlet 71.

As shown in FIG. 8, the disc is provided with six sets of the springs 55and 56. The spring sets have same structures. Referring to FIG. 9, thesprings 55 and 56 are covered by hollows 75 and 76 formed in the cases57 and 58. The hollows 75 and 76 are covered by annularly extendinghollows 77 and 78 formed in the cases 60 and 61. The springs 55 and 56are contact with spring seats 80 supported by side edges of the recesses54 in the member 53 and inner end surfaces 81 and 82 of the hollows 75and 76.

In this modification, whole of the springs 55 and 56 function withoutchanging an incline shown in FIG. 10. A torque supplied from a flywheelto the cases 60 and 61 is transmitted to an output shaft through pins62, the annular member 53, the springs 55 and 56, the covers 57 and 58,the pins 69, the flange 51 and the hub 50. When the torque istransmitted, the springs 55 and 56 are compressed, and the cases 60 and61 as well as the annular member 53 torsionally turn with respect to thecover 57 and 58 as well as the flange 51. The compression of the springs55 and 56 cause the spring seats 80 (FIG. 9) to push and discharge theoil in spring chambers 85 into spaces 86 between the covers 57 and 58and the member 53, which causes a resistance, so that a resistance forceis loaded to the spring seats 80, and a hysteresis h is acquired in acharacteristic X1, as shown in FIG. 10. The hysteresis h changes inaccordance with torsional angular speed. Therefore, torque vibrations inboth of starting operation and high speed driving can effectively beabsorbed. According to this modification, since the oil inlet 71 can bearranged at a portion of the case 61 between two sets of the springs 55and 56, a sufficient space can be obtained for disposing the nut 73 inFIG. 7. Therefore, the nut 73 can easily be welded.

The embodiment in FIG. 7 may employ torsion springs which operate at twoor more steps. The embodiment in FIG. 1 may employ torsion springs whichoperate at two or single step throughout the operation.

The invention may be modified as shown in FIGS. 11-13, in which samemembers as those in FIGS. 1-5 and 7-9 bear the same reference numbers.

Referring to FIG. 11, radially spaced protrusions 130, which extendannularly as shown in FIG. 12, are formed at both side surfaces of aportion radially inside openings 20 in a hub flange 2. Annular members132 are fixed by screws 131 to inner surfaces of radially inner portionsof cases 3 and 4, respectively. The members 132 are provided withradially spaced annular protrusions 133, which engage with theprotrusions 130 with narrow spaces therebetween. Each pair of the screws131 are screwed into a female thread of a tubular collar 134, whichenters a circumferentially long aperture 135 in the flange 2. Theprotrusions are not formed at portions around the apertures 135 in themembers 132.

Referring to FIG. 13, when the cases 3 and 4 move in a rotationdirection A, a spring seat 125 at the right in FIG. 13 also moves in thedirection A, so that a oil is compressed between a pair of the seats125. The compressed oil is discharged to the backs of the spring seats125 through spaces 145 in FIG. 11 between the spring seats 125 (FIG. 13)and inner surfaces of radially outer portion of hollows 21 and 22. Thecompression and the discharge of the oil causes a resistance force to betransmitted to the cases 3 and 4 and the flange 2 through the seats 125.A resistance force caused by viscosity of the oil in the spaces 41, inother words, caused by shearing the oil in the spaces 41, is applied toportions 3a, 4a and 2a of the cases 3 and 4 and the flange 2 which faceeach other.

Further, the protrusions 132 also torsionally turn together with thecases 3 and 4 with respect to the flange 2, so that a resistance forceis caused by viscocity of the oil between the protrusions 130 of theflange 2 and the protrusions 133 of the cases 3 and 4, in other words, aresistance force is cause by shearing the oil therebetween, and isapplied to the flange 2 as well as the members 132 and the cases 3 and4. This resistance force is large, because the protrusions 130 and 133has large surface area.

As detailed hereinbefore, the resistance force is caused in the oil bythe torsion of the cases 3 and 4, and a torque corresponding to theresistance force is transmitted from the cases 3 and 4 to the flange 2through the oil (not through the springs 17 and 18), so that, as shownin FIG. 14, a characteristic X including a hysteresis h is acquired.

Structures in FIGS. 15 and 16 may be employed in some or all of openings151 in the hub flange 2.

Referring to FIG. 15, a pair of spring seats 152 of small diameter arearranged at both ends of each spring 18 of small diameter. Both ends ofeach spring 17 of large diameter are supported by annular spring seats153 which are slidably fitted around the seats 152. The spring seats 152protrude distance L or L' rearwardly beyond the spring seats 153. Eachside edge 155 of the openings 151 is hollowed at its middle portion, sothat both of the seats 152 and 153 may be supported on the edge 155 whena torsion angle is zero as illustrated. referring to FIG. 16, when thetorsion angle is zero, the inner end surfaces 26 and 27 of the hollows21 and 22 in the cases 3 and 4 are in contact with the spring seats 152and are apart from the spring seats 153 with spaces L and L'corresponding to said distances L and L' therebetween.

In the structures in FIGS. 15 and 16, when the torsion angle of thecases 3 and 4 is small, only the spring 18 is compressed. When the cases3 and 4 torsionally turn a degree corresponding to the space L or L',the inner end surface 26 and 27 contact the spring set 152, and,thereafter, the spring 17 is compressed. Consequently, the springs 17and 18 operate at two steps. The moving spring seat 152 and 153 compressand discharge the oil from each spring chamber, which causes ahysteresis.

In the embodiment in FIG. 11, a single spring may be employed instead ofeach pair of the springs 17 and 18.

Since the protrusions 130 and 133 have the large surface area, a largehysteresis can be acquired on the protrusions 130 and 133, so that thehysteresis is not essentially required to be caused by the structuresincluding the springs and the seats. Thus, the spring seats 125 (or 152in FIG. 15) may be eliminated, and the spaces 41 and 145 may be widened.

The protrusions 130 may be formed independently of the flange 2 andfixed to the flange 2. The protrusions 130 and 133 may be formed only onone side surface of the flange 2 and one of the cases 3 and 4 facedthereto.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form may be changed in the details ofconstruction and the combination, and arrangement of parts may beresorted to without departing from the spirit and scope of the inventionas hereinafter claimed.

What is claimed:
 1. A damper disc, comprising:a spline hub; a radialflange formed at the hub; a pair of cases rotatably mounted on thespline hub and innerconnected at the radially outer end thereof, saidpair of cases being disposed, respectively, on opposite sides of theflange; circumferentially spaced plural compressible coil springassemblies operably connecting the cases and the flange together, atleast one of said coil spring assemblies including axially aligned andconcentric first and second coil springs, said first coil springdisposed within said second coil spring, such that one of said springsbegins to compress before the other; at least one side face of saidflange, radially inward of said spring assemblies, having a plurality ofradially spaced annular projecting protrusions with radially spacedannular recesses therebetween; at least one of said pair of cases havinga plurality of radially spaced annular protrusions projecting inwardlyinto said annular recesses between said spaced annular protrusions onsaid flange and forming narrow oil receiving recesses between saidflange and said case protrusions; a sealed oil chamber formed aroundeach of said spring assemblies and said flange and case projectingprotrusions and said cases and having only sealed narrow spacesconnecting said spring chambers together and said narrow oil receivingrecesses together; and spring seats disposed at both ends of each springassembly, said chamber and each narrow oil receiving recesses beingfilled with oil, so that said oil provides a resistance force to themoving spring seats and to the relative movement of said radially spacedannular projecting flange protrusions relative to said radially spacedannular projecting case protrusions.
 2. A damper disc, as recited inclaim 1, in which the side faces of said flange radially inward of saidspring assemblies each have a plurality of radially spaced annularprojecting protrusions with radially spaced annular recessestherebetween and each of said pair of cases has a plurality of radiallyspaced annular protrusions projecting inwardly into the annular recessesbetween the spaced annular protrusions on the flange face facing theretoand form narrow oil receiving recesses between said flange and said caseprotrusions.
 3. A damper disc, as recited in claim 2, in which said oilchambers are only slightly larger in cross-section than said springseats to enable said spring seats to function as hydraulic pistons,wherein at least one of said spring seats corresponding with said firstand second springs has two portions movable independently from eachother, a first portion supporting said first spring and a second portionsupporting said second spring, said first portion engaging a projectionon said flange to cause said first spring to compress before said secondspring which is not engaged with said projection.
 4. A damper disc, asrecited in claim 1, in which said oil chambers are only slightly largerin cross-section than said spring seats to enable said spring seats tofunction as hydraulic pistons, wherein at least one of said spring seatscorresponding with said first and second springs has two portionsmovable independently from each other, a first portion supporting saidfirst spring and a second portion supporting said second spring, saidfirst portion engaging a projection on said flange to cause said firstspring to compress before said second spring which is not engaged withsaid projection.